XVI IXTRODUCTIOX. 



Some species come in flights at more or less distant intervals of 

 time, such as the Crossbill, Sand-Grouse, Quail, Bittern, SnoAvy 

 Owl, Kough-legged Buzzard, Grey Phalarope, Skuas, &c., their 

 occurrence at other times being rare, so that the Authors think 

 it of much importance that the dates of such events should, be 

 carefully recorded in Local Faunas, in order that the route the 

 birds follow may be ascertained. 



The difficulties experienced have been due rather to the great 

 abundance of material that has come to hand than to lack 

 of information with regard to most species, and it has often 

 been hard to decide what to reject or what to retain from the 

 mass of observations available in various publications or kindly 

 contributed by friends, and in some instances the Authors had 

 collected forty or fifty references for a single bird. 



No bird which has not been actually obtained and examined 

 by competent persons has been admitted in the census of species 

 occurring in the county, with the exception of the Black-headed 

 Warbler, "Water-Pipit, and Hawk-Owl, about which the Authors 

 entertained no doubt ; perhaps strictly they should liave adhered 

 to their rule in these instances as well. 



They have considered it advisable to mention in their proper 

 place all birds which have been recorded as occurring in the 

 county, even though they have thought it necessary to exclude 

 them in the enumeration of species, either because they have not 

 been actually obtained, or were incorrectly identified, or were 

 admitted into previous lists upon insufficient evidence ; all such 

 species are included in square brackets [ ]. 



No doubt it is most desirable to eliminate all bii'ds from the 

 Count}'^ List that have been added to it uponinsufiScient eA'idence; 

 but at the same time it seemed proper that the reasons for so 

 doing should be stated in all cases, otherwise it would be impos- 

 sible for a student to ascertain whether a species was omitted 

 puiposely or through oversight. The Authors have preferred to 

 allow their readers to judge for themselves by citing all the evidence 

 available in these cases. 



While they are only too conscious of omissions and possibly 

 of errors which they lear may be detected in their work, and for 

 which they venture to apologize in advance, they yet hope that 



